Fossil fuel such as oil or coal is an energy source essential to mankind, but generates a large amount of carbon dioxide (CO2) during the use thereof, undesirably causing global warming and serious climate change. Accordingly, mandatory CO2 emission regulations will be applied in the future. Moreover, although a variety of energy sources have been developed to replace fossil fuel, the International Energy Agency (IEA) has reported that in terms of total energy demand, fossil fuel will fill 70% or more of the demand through 2050.
Thorough research around the world is ongoing into the reduction of carbon dioxide and the fixation and storage of carbon dioxide in facilities, such as large petrochemical plants, thermal power plants and steel mills, where a large amount of carbon dioxide is emitted at high concentration. The currently available carbon dioxide fixation methods involve dissolving carbon dioxide in water to store it, compressing carbon dioxide to store it in the deep seabed, storing carbon dioxide in tunnels, photosynthesizing carbon dioxide using algae, or precipitating carbon dioxide into calcium carbonate.
However, these conventional carbon dioxide fixation methods are problematic because the fixation efficiency of carbon dioxide is low, and the large volume of the material produced in this procedure needs a large storage space, or because high cost is required to perform fixation and storage of carbon dioxide. Furthermore, it is difficult to accomplish cyclic utilization of resources including fixation of carbon dioxide and recycling of carbon from fixed carbon dioxide. Such methods are not regarded as a fundamental solution of carbon dioxide problems.
For example, the following Patent Document 1 discloses a method of fixing carbon dioxide, wherein slag as a byproduct of a steel making process is reacted with carbon dioxide so that carbon dioxide is fixed on the surface of slag, and thus the slag having fixed carbon dioxide functions to prevent formation of high alkaline dissolved water, colored water, and cloudy water and precipitates and is thereby used as aggregate for public works. However, this method suffers because limitations are imposed on materials able to fix carbon dioxide and carbon resources of fixed carbon dioxide cannot be reused.